custom sound chips?

I've always wondered how these doorbells and other such devices play a particular recorded jingle or a song.I think its possible to make circuits which can play custom tunes set by us(maybe using a PC).Could you please give me a brief idea on how this is done?

Did you make this instructable?

Pick up a cheap 9V sound recorder module from Radio Shack and record whatever sound you want into it. The microphone on the unit can be replaced with any analog audio jack you want so you can record something from the PC or your MP3 player.

You said it,steveastrouk.We don't have a radioshack here but there are a lot of electronics dealers in the city.Only thing is that ,will have to spent atleast half a day going from shop to shop looking for the right product. So,sound recorder module it is...thanks